1. Meet the electron……

2. Why did Bohr think electrons are in energy levels around the nucleus?

3. He saw colored light when things burn and wondered why.

5. Wavelength and energy: Bohr knew light is a form of energy and light is a wave. Different colors of light have different wavelengths which relate to their energy **Draw the below diagram of a wave**

6. Short wavelengths have more energy
Short wavelengths have more energy. (There are more “waves” in the top one.)

8. Check for understanding
Which type of wave has more energy gamma waves or radio waves?
2.How can you tell?

10. Check for understanding
Which type of wave has more energy gamma waves or radio waves?
Gamma
2.How can you tell?
Shorter wavelength

12. Each element has it’s own light pattern. Can use to ID element.

13. Wave Model of Atom replaces Bohr Model adds energy sublevels called s, p, d, f orbitals.

16. Number of electrons in the energy sublevels
Each sublevel holds a certain number of electrons
Each “s” can have up to 2 electrons
Each “p” can have 2 electrons x 3 p= total of 6 electrons
Example- Li 1s22s1
F 1s22s2p5
*The s level must first be filled, then the p level.

17. Electron configurations are the addresses of the electrons
Electron configurations are the addresses of the electrons. They list the energy sublevels and the number of electrons in each sublevel for an element.
1s22s22p6
Energy Level Number of electrons
Sublevel
**The last energy level tells you the Period #- 2 in this example.
Add up the exponents for sublevel 2 only (2+6= 8)- 8 tells us the Group #
-The element is in Group 8, Period 2
Electron Configurations

19. Superscripts/exponents are the number of electrons
Superscripts/exponents are the number of electrons. Add them together and get the total number of electrons. Use this to ID an element. (Remember APE)
Try it, what element has the following electron configuration?
1s22s22p2
Identify the element

20. Answer: 6 electrons - Carbon
Superscripts are the number of electrons. Add them together and get the total number of electrons. Use this to ID an element. (Remember APE)
Try it, what element has the following electron configuration?
1s22s22p2
Answer: 6 electrons - Carbon
Identify the element

21. List the noble gas that comes before the element and complete with the last energy level and sublevels.
Example: [Ne]3s23p2
To ID the element find Ne and move 4 atomic numbers passed Neon. What element did you find?
***(Add these notes in)***
OR look at the “3” this is the LAST energy level (also the Period #)
Then, look at the exponents (2, 2). Add these up= 4 this is your Group #
Short version of electron configurations

22. List the noble gas that comes before the element and complete with the last energy level and sublevels.
Example: [Ne]3s23p2
Group # 4 (2+2= 4)
Period # 3 (last energy level)
Answer: Silicon
Short version of electron configurations

23. Prior Example
Example: [Ne]3s23p2
When you see [Ne] “ [ ]” it means refer back to. So you would need to look at Neon’s electron configuration.
Ne is 1s22s22p6
Then add the 3s23p2
So Silicon’s electron configuration is really
1s22s22p6 3s23p2
Brackets